Charles



Dec. 4, 1928. 1,693,599

c. GILLINGS TELEPHONE SYSTEM Filewb lg iflg fiheets-sheet 1 Fly: 1

F251: 5 1? INLDIIIIQIAPSUAL Z Charles 511111195 Dec. 4, 1928. 1,693,599

C. GILLINGS TELEPHONE SYSTEM c Flled Feb. 10, 1925 Z Q EH Sh e}; 2

-Im.ran ur' Charles E-zllmgs individual to the private branch exchange Patented Dec. 4, 1928.

unites stares tease-99 rara roFF cE- CHARLES GILLINGS', or LIVERPOOL, ENGLAND, Assrenoa, BY MESNE ASSIGNMENTS,

T0 AUTOMATIC sane-rare Inc, on cnroaeo, ILLINOIS, a ooaronarron on DELA- WARE.

Application filed February 10, 1925, Serial No.

The present invention relates to improved trunking arrangements for use in automatlc or semi-automatic telephone systems with a view to reducing the cost of providingwhat ber. of lines were greaterthan 10, it was 7 arranged that automatic movement should take place inboth directions of motion after a certain digit had been dialled. These special switches have usually been segregated into groupsseparate from the regular connector-switches; moreover they have generally been of the" connector-type having means'for ringing the calledsubscriber and for supplying feed current to both Calling and called parties. They are accordingly expensive and as a large number have to be provided in connection with a large group of lines, the cost of providing service to such P. B. subscribers may be very heavy. V

This objection may be largely overcome according to one feature 01 the'invention by employing outgoing secondary hunting switches for selecting anidle private branch exchange line, these switches having the'same controlling means asthe switches used "in the regular trunking with special repeaters lines for effecting the si'gnalling oi the private branch exchange. These repeaters may be individual to eachline or may be associated with the hunting switches.

According to another feature of the invention connections are extended to private branch exchanges having a large number of lines with the same numerical designation over non-numerical secondary, switches reached over fewer switching stages than are employed for connecting with individual subscribers lines.

A further feature of the invention is that private branch exchange lines when in large groups are adapted to be selected direct or through the intermediary of secondary hunting switches only from the banks of group TELEPHONE I.

8,271, and. in Great BritainFebruary 15, 1924.

selector switches, signalling means being provided beyondthe selector switches so that no modification whatever is required of the selector switches used for t'raiiic to both private branch exchange lines and individual lines. I

Still another feature of the invention is that some of the lines from a private branch exchange terminate in repeaters including battery feed and supervisory arrangements I so as to permit of traffic in both'directions while others, are equipped for trailic in one di- I understood however that various modifications of the arrangementsshown might be employed withoutexceeding the scope of the invention. r U i V Figurel-shows diagrammatically one ar- 7 rangement according to the invention and Figure 2 shows in moredetail the bank wiring. used for the third selectorof Fig 1. Figure 3 shows an alternative arrangement for rather larger groupsa modification'of the bank wiring being indicated inFig. 4. Figs. .5and 6 showthe actual. circuits of the.r e-- peaters used and the connecting arrangemore fully underbut more than 10 lines and that the subscriber at substation A wishes to extend a connection to it. He thereforeremoves his receiver and takes into use the first selector ,D by way of his line switch (hand selector D when op erated seizes the second selectorE. The particular level of E to which the switch is now operated does not extend to connector switches, as is usual assuminga10,000line exchange, but to third selectors such as F; These selectors are of the so called large ca pa'city typehaving two sets of wipers and corresponding contact banks and arranged for simultaneous hunting over bothbanks. Switches of this type are described for in stance in British Patents Nos. 170,385 and installation. it is then clearly neccssar 186,037. Access may thus be had to as many as 20 lines X, each of which leads to a repeater R such as shown in F ig. 5 or Fig. '7. This repeater is adapted to control the ringing or other signalling and supervision to supply feedcurrent to both parties and to include the necessary switching circuits for p ornitting outgoing calls to be established.

Generally speaking the operator in charge of the P. B. X. switch board is on duty only during the daytime and it the building is not entirely deserted at night it is usual to connect through night service lines to one or more telephones located at selected points in the for these lines to be first choice to the automatic switches, otherwise it would be impossible to establish connection with them at night. Thus in Figs. 1 and 2 assuming tour night so: vice lines X are provided these will be connected to the first and second contacts in each bank. In order, however, that a calling party may be able to gain access to a particular night service line, it is also arranged that they are also accessible from ordinar 1 straight line connectors as indicated at Z. Thus if the caller does not know the night servi number of the particular line he requires he may dial the regular P; B. X. number and will then obtain connection with one of the n ght service lines unless they are all alreac in use. He may then enquire for the number of the particular line wanted and if he dials this he will obtain connect-ion over the ordinary connec tors and one of the lines Z. The nigl t service number need bear no'relation to the ordinary P. B. X. number. If the calling par Uy knows the night service number of the particular line he wants, he will of course dial it in the first place, but he is not deniec. service in case he does not know it. Clearly also so ess may be obtained to the night service lines over th regular connectors in the daytime though as these lines are first choice they will probably generally be busy.

In Figs. 1 and 2, the lines X extending from the repeaters 13. lead to line switches and are used for establishing outgoing connections in the manner described in connection with Figs. 5, 6 and 7. The lines Y in F 1 are usedonly for outgoing connections, it b ing assumed in this case that the outgoing trafic is somewhat heavier than the incoming trafiic;

peaters have to be provided. (I lines equipped for outgoingtrafiic only will be taken into use by the operator in preference to the lines equipped for both way workmg.

Figs. 3 and 4 show alternative arrangements for rather larger groups of lines. hie maximum number allowed for 205 i:. Fig. 3 including 5 night service lines and 1 in Fig. d'including i night service lines. Suppose that subscriber A takes into use first selector D and second selector E by way of his line switch C and then operates selector E to the particula level corresponding to the B. X. in the case shown in Fig. 3, each contact in this level instead of leading to a connector switch as it would :to' indi.' lual scribers lines, extends to line switch access for instance to 25 lines so a ouble hunting operation is obtained. 11 is oi the homing type, that is to urns to a normal poition alter use the w' is so a ran d that the live so- .ice ines are connected to its first fivecontacts so as to be nrst choice. These rive contacts are 'multipled between the line switches connected to each of the ten con acts of the selector level, but. the rcn-a i it re .ining twenty t in e ch cafe are connected to a dit t group of lines; henc with this arrangement a maximum of lines is obtained. Each of these lines will in the previous case have a repeater Pf associated with it to provide bat-t ry feed and permit of both way s "itches LS connected as et'ore to line see may be or the type in which in this which the wipeused and each contact of each switch accessible from a one level may extend to a separate line. Mepeatcrs R individual to the lines are again employed and the night service lines are preferably accessible also from ordinary connectors as before.

The actual repeater circuits shown in Figs. 5, 6 and 7 will now be uiefly described. When the repeater in Fig. 5 is n into use, leads 1 and 2 will be connected over the calling loop and a circuit will therefore be ccmpieted by way of the normally closed contacts controlled by armatures 6 and 7 for line relay e.

Relay 1 upon operating, at armature 5 completes a circuit for change over relay 9. The latter on operating, at armature 11 connects earth to release trunk conductor 3, and at armaturcs 10 and 1:2 disconnects the outgoing conductors 16 17 from the winding of the line relay ot' the line switch ant. earth respectively and conipletes the following circuit battery, retardation coil 18, front contact armature 12, lead 17, normally closed controllec by dialling key K, lower left hand winding of repeating coil, windings of olarized relay 20, upper left hand winding 01" the repeating coil normally closed springs of key K, lead 16, armature and its front contact, windoi relay 8 to earth. Relay 8 cannot operate in this circuit owing to the resist ance polarized relay 20, but tle latter operates and completes a circuit follows:

1. s remain on the contacts lastbattery, armature 25 and its had: contact, springs 21, call lamp 27 to earth. Lamp 27 therefore lights and the operator on noting this inserts. the answering plug of an idle cord circuit, for instance plug P, into the Jack J. A circuit is thereupon completed over the sleeve of the jack for lighting the supervisory lamp 28and a circuit is-also completed from battery, lower left hand winding 01 the repeating coil in the cord circuit,

supervisory relay, ring of plug, ring of ack, lower right hand'winding oi the repeating coil in the trunk circuit, springs 22, upper winding of relay 23 to earth. Relay 23 is now operated'and at armature 25 completes a locking circuit through its lower winding at the same time extinguishing lamp 27' and at armature 2% places a shunt including resistance 26 across the windings of polarized relay 20. This shunt is not sutlicient to de energize relay 20 but allows enough current to pass to energize relay 8. Relay 8 which now operates, at armatures 6 and '7 reverses the current back over the calling line for me-v tering, supervision or similar purposes. The operator may now complete the connection locally with the calling plug P of the cord circuit, supervision from thisside being by ueans of the lamp 29 asusual. 7

When the conversation is finished both parties will replace their receivers' When the receiver is hung up at the called substa-,

tion, the supervisory relay will de-energize and lamp29 will light. When the calling party hangs up, linei'elay 4 will deQenergize and by releasing armature 5 cause relay 9 to deenergize also. Relay 20 is thus again placed across. conductors 13 and 14 and the current fiow from the line relay of the line switch is not in the right direction, to maintain relay 2O operated. Relay 20'upon deenergizing opens at springs 22 the circuit through the upper winding of rela-y23' and the supervisory relay inthe answering portion ot the cord circuit so that lamp 28 lights.

The operator then removes both plugs and all the apparatus is restored to normal. will be understood of course, that the line relay or" the line switch connected to conductor 13 is unable to energize in series with relay 2O owing to the high resistance of the I latter.

For outgoing calls the operator will insert aling plug. for instance the plug P of the cord circuit shown into the ack J and will then throw the dialling key K. occurs, the line switch is able to operate in the i -1ual manner, the connection of earth to L5 which then ensue: serving to busy the repeate to incoming calls. The operation of th dial S sets the automatic switches in known manner and when the called party replies the reversal of current over the line operates polarized relayQO to give theP. B. operator answering SUPSIVISIOILH The whole lvVhen this connection is released when the operator withdraws the plugs after both subscribers have hung up.

Referring now to Fig. 7, the arrangement there shown is suitable for use where the sig naling devices at the P. B. X. respond to ringing current.- In this case when the repeater is taken into use a Oil Cull; is completed over leads 31 and 32 and the normally closed springs controlled by armatures a5 and 4G for line relay 34-.- .Relay 34: upon energizing, at armatures 39 and l0 disconnects con-1 ductors 4-2 and s3 extending to the associated line switch and prepares the ringin' circuit,

ture gives the calling party ringing induction by way of the small condenser 51.

lVhen the attendant at the P. B; X. replies, relay 53 is operated by direct current and at armature 55 .coiiipletes a locking circuit for itself and at armaturefi opens the circuit of relay 48.

the speaking circuit, battery-being fed from the windings of backbridgerelay. This therefore operates, at armatureA-T opens a further point in the circuitoi relay 48 and at armatures 45 and idi'eveises current back over the calling loop so asto give supervision vin'the usual manner. Therelease of .the connection takes-place as usual when the calling party hangs up,;the ensuing deenergization of relay 3% bringing down-relays 4a, 37 and 53' h Outgoing connections are completed over conductors 56 and 5?, armatures 39 and i0 and their back contacts and conductors'iQ and 43 in the usual manner. Theearth fed back on conductor ll by the operation of the line switch serves to energize relay 3? and b 5' o at. 1%.?8 b1 -Tm t1 1 ns. y opera m arm u-e o usws 1e 1e pea-tor to incoming calls in known manner;

l Vhat I claimis:

1. In atelephone system, regular subscribers lines, selector switches, agroup of private branch exchange lines, means for operating one of said selectors to extend a connection toward one of said regular subscribers linesor to complete a connec-tionto an idleone of said private bi aiich exchange lines a s'iecial re eater individual to each of said private branch exchangelines, and

means included in said repeaters for signalling over the private branch exchange lines.

2. In a telephone system,individual lines, selector switches, connector switches, means for operating said selector switches and said 7 The latter therefore de-encrglass and at armatures 49 and-52 completes said individual lines, branch exchange lines, ing switches, inc us for selecting an i in said group through the i I said h uiting switches on of said s lector switches means provided beyond so nailing said private branch e In telephone systen l a branch exchange, tru ing' said exchanges all or. to handle branch to air individual ringing a. In a telephone system, main and branch from the main exchange to the -anch ct:- change, a small group t other tr cnlr lines for handling night calls from to the branch exchange, the lines being; accessible to connectors change, and selectors in the main havino; access to all said trunlr lin lines being so connected to the so however, that the night lines at 5. ln a telephone system, a a branch exchange, a trunl: said exchanges, nieans includ for extending callin line to s V. a. repeater in the in in excl-iang-e included in said trunk line, and means includ ng li; e re ay in said repeater ene 'ised res-por to the seizure of the trunL line for ting signalling current over the trni 6. in a telephone system, a main exc a branch exchan 'e, groups 01" l switches in the main exchange, groups sor ice trunks accessible to said respectively, ccnirion group or night service trunks accessible the switches of all said groups, the s i trunks beln so connected in the banl: cswitches th t they are first choice, niinals for all said trunks at the branch. enchange.

7. A telephone system s claimed i1 6 in which selectors are inserts the hunting swit hes and in wlnc selectors as first choice.

8. In a telephone system, a trunk l'ne divi ded into two sections normally disconnecte l 9. In a telephone system, a trunk line di- I action of sa d sections, a line relay in said eneater responsive to the seizure of said run: line for connecting the sections of said unl: line together, a ringing relay in said repeater responsive to the initial operation or said line relay for applying signalling current to said trunk line, and a ring cut-oil :elay included in said repeater and operated over said trunk in e for disconnecting said current f om aid trunk line.

i In a telephone system. a trunk line divided into we normally disconnected sections, a ringing repeater the junction of sale sections, a, line relay in said repeater responsive to the seizure of said trunk line tr conn cting'together said normally disconnected sections, a ringing relay in said repeater responsive to the initial operation of said line relay for applying ringing current to said trunl: line, a ring-cut-otl relay in said repeater, subscriber controlled means for operating said ring-cut-ofi relay, and means controlled by said ring-cut-ofi relay for disconnecting said rnging current.

11. In a telephone system, main and branch C m. cnange lines connecting the main and branch exchanges, selector switches in the main exchange, and means whereby said selectors have direct access to certain lines of said group While the reinainin lines of said group accessible to said selectors only through non-numerical hunting switches.

12. ln a telephone system, main and branch exchanges, a group of private branch eX- change lines connecting the main and branch exchanges, selector switches in the main e chan e, means whereby said selectors have direct access to certain lines oi said group w e the remaining lines of said group are accessible to said selectors only through nonfrom the main exchange to the branch enchange, a small group o1 other thrunk lines from the main eX-- for handling night call:

change to the branch exchan and selectors in the niain exchange having access to all said trunk lines, the night lines bein irectly connected to the selector banks as first choice and the day lines being connected to tne selector banks only through non-numerical switches.

1%. In a telephone system, a main exchange, exchange, groups of hunti: switches n the resin elzchange, groups of day serx' ice trunks accessibl to said groups of switches, respectively, a group of night serbeing so connected in the banks of saidselec- 5 tors that they are first choice, and terminals for all said trunks at the branch exchange.

15. In a telephone system, a group of pri- Vate branch exchange lines, and a repeater individual to each of said lines for use by such lines When calling andfor transmitting 10 ringing current and feeding talking battery to said lines When called.

In testimony whereof I affix my signature.

' CHARLES GILLINGS. 

